Definition of "collimator" [col•li•ma•tor]

• A device capable of collimating radiation, as a long narrow tube in which strongly absorbing or reflecting walls permit only radiation traveling parallel to the tube axis to traverse the entire length. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "A collimator is a simple device that uses a reflective surface and lenses to replicate a target at infinity."
• "I do not carry ammo in mine - that's a big NO-NO in California South - but I carry several calibres in "bore snakes" and a collimator, plus a copy of local legislation, to balance that."
• "A boresighter, or collimator, can save you untoldanguish by showing you where your scope is aiming, as opposed to where youthink it's aiming."